I followed Eric's offline suggestion and edited a line to use polymer-dev. Then with:
cd pica
bower install Polymer/polymer-dev
I was able to make progress. Now I am stuck in platform.js
I tried
bower install Polymer/platfor-dev
Then I reissued vulcanize.
However my platform.js is still compresssed, making debugging very painful. There must be some where that I need to replace an include of platform.js with another something. But the string
<script src="../platform/platform.js"></script>
appear in a lot of files so I guess this is not the right process.
Any hints?
jjb